Launch scrolling screenshots directly from ScreenshotController

We switched to routing the LongScreenshotActivity launch through
ActionIntentExecutor, but this inadvertently broke long screenshot
launching in work profile because the cross-profile launching doesn't
work. Reverting to previous behavior of directly calling startActivity
within ScreenshotController.

Bug: 329659738
Bug: 339372163
Fix: 339372163
Flag: EXEMPT bugfix (reverting to previous behavior)
Test: manual, taking scrolling screenshots in personal+work profile and
verifying that long screenshot activity is successfully started

Change-Id: Ifb6c957ae165f3e469d19d4b1becbca4c1edf7ca